Mybatis查询是否存在

FooMapper.java

Integer exist(Map<String, Object> paramMap);

FooMapper.xml

<select id="exist" parameterType="Map" resultType="Integer">
    select 1 from foo_table
    <include refid="conditions"/>
    limit 1
</select>

FooService.java

  public boolean exist(Map<String, Object> paramMap) {
      return FooMapper.exist(paramMap) != null;
  }